1. Field of the Invention
This invention relates to novel polyurethane compositions derived from the reaction of diisocyanate and a particular class of polyols, e.g., diols. More especially, this invention relates to the use of such novel polyurethanes as dispersants for lubricants and fuels. More especially, this invention relates to lubricant and/or fuel compositions containing, as dispersants, the novel polyurethane condensation polymers of the invention.
2. Discussion of the Prior Art
Numerous lubricant oil dispersants are known for use in motor oil compositions. Many of these dispersants are in the form of large organic chemistry molecules possessing a variety of functional groups. For instance, in U.S. Pat. No. 3,573,205, there is disclosed lubricant compositions which are the reaction products of diisocyanates and alkenylsuccinimides of polyalkylene amines. These reaction products can be represented by the following formula ##STR1##
Thus, the condensation polymers are characterized by urea functions which are formed by the reaction of the diisocyanate with a primary or secondary amino group, the alkenylsuccinyl group being pendant to the polymer chain.
Other dispersants for use with lubricants are disclosed in U.S. Pat. No. 3,850,826, which discloses the preparation of polyamides as an initial step by high temperature condensation reaction of amines bearing two secondary amine groups with an alkenylsuccinic anhydride group. The polyamide is thereafter reacted with the diisocyanate, whereby the terminal secondary amino group of the polyamide reacts with the diisocyanate to form a polymer via the formation of urea moieties.
Neither of these prior art dispersants are characterized by urethane or ester functions in the product.
In the continuing quest to provide new and improved polymeric dispersants for lubricants and/or fuels, it became desirable to provide a lubricant and/or fuel dispersant which contained urethane groups. More especially, it became desirable to provide such an improved urethane-containing polymer which would pass the rigorous standards required of modernday lubricant and/or fuel dispersants. Still moreover, it became desirable to provide a novel backbone for the polyurethane polymers, which backbone could be supplied by a wide variety of organic chemicals containing any one of a number of functional groups. Specifically, it became desirable to provide a polyurethane polymer of relatively low molecular weight and good dispersancy containing, pendant from the polymeric chain, an alkyl or alkenyl moiety of substantial chain length and a moiety within the polymer chain itself composed of an alkylene or arylene moiety having 2 to 20 carbon atoms, optionally containing inert functional groups such as tertiary amino groups. These and other objects are accomplished in accordance with the present invention, which is discussed below.